U.S. patent number 4,812,445 [Application Number 07/041,563] was granted by the patent office on 1989-03-14 for starch based encapsulation process.
This patent grant is currently assigned to National Starch and Chemical Corporation. Invention is credited to James Eden, Ralph Trksak, Robert Williams.
United States Patent |
4,812,445 |
Eden , et al. |
March 14, 1989 |
Starch based encapsulation process
Abstract
Virtually any material may be encapsulated in a starch matrix by
combining the material with a high temperature-stabilized
dispersion of starch, optionally in the presence of salt. The
temperature-stabilized starch dispersion acts as a protective
colloid, encasing the material to be encapsulated. Upon subsequent
rapid cooling of this mixture on a chilled surface the starch
polymer chains collapse upon themselves, forming a firm sheet or
the like and encapsulating the core material. The sheet can then be
cut, chopped or sliced in the wet state, then dried and ground to
yield particles.
Inventors: |
Eden; James (East Millstone,
NJ), Trksak; Ralph (Manville, NJ), Williams; Robert
(Homosassa, FL) |
Assignee: |
National Starch and Chemical
Corporation (Bridgewater, NJ)
|
Family
ID: |
26682975 |
Appl.
No.: |
07/041,563 |
Filed: |
April 23, 1987 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11952 |
Feb 6, 1987 |
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Current U.S.
Class: |
514/60; 264/217;
264/218; 424/484; 424/485; 424/488; 424/499; 514/778; 514/965 |
Current CPC
Class: |
B01J
13/04 (20130101); A23P 10/30 (20160801); A23L
27/72 (20160801); Y10S 514/965 (20130101) |
Current International
Class: |
A23L
1/22 (20060101); A23L 1/00 (20060101); B01J
13/04 (20060101); A23L 001/22 (); A23L 001/226 ();
A61K 009/26 (); A01N 025/28 () |
Field of
Search: |
;514/60,778,965
;424/484,485,488,499 ;264/217,218 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0145846 |
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Aug 1984 |
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EP |
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1072795 |
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Jun 1967 |
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GB |
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Primary Examiner: Griffin; Ronald W.
Attorney, Agent or Firm: Dec; Ellen T. Szala; Edwin M.
Parent Case Text
BACKGROUND OF THE INVENTION
This is a continuation-in-part of copending application Ser. No.
011,952 filed Feb. 6, 1987, now abandoned.
Claims
We claim:
1. A process for encapsulation of materials in a starch matrix
comprising the steps of:
(1) slurrying the starch in water;
(2) thoroughly dispersing the starch in the slurry by injecting
steam at a pressure of at least 110 psi into the slurry to raise
its temperature to 120.degree. to 180.degree. C. at a pressure of
55-120 psi or above;
(3) adding to the dispersion the material to be encapsulated and
effecting intimate mixing of the latter therein;
(4) spreading the resultant mixture on a chilled surface;
(5) recovering the encapsulated material in sheet form; and
(6) cutting or grinding and drying the resultant matrix of starch
and encapsulated material.
2. The process of claim 1 wherein the material to be encapsulated
is selected from the group consisting of the flavors; seasonings;
natural and artificial sweeteners; pigments; metallic powders;
latices; oils; plasticizers; herbicides; insecticides; fungicides;
nematicides; bacteriocides; rodenticides; molluscicides;
acaricides; larvacides; fumigants; animal repellants; insect
repellants; plant growth regulators; fertilizers; pheromones; odor
producing compositions; catalysts; adhesives; pressure sensitive
color formers; electrostatographic toners; pressure rupturable
lubricants; antifoulants; phase change materials; fire
extinguishers; corrosion inhibitors; defoamers; sizing agents;
thickeners; sub-cutaneous medications; unsaturated fats and
acidulants.
3. The process of claim 1 wherein up to 50% of the starch is
replaced by a water soluble hydrocolloid.
4. The process of claim 3 wherein the water soluble hydrocolloid is
selected from the group consisting of polyvinyl alcohol,
carboxymethylcellulose, hydroxyethylcellulose, polyacrylic acid and
polyvinyl pyrrolididone.
5. The process of claim 1 wherein the starch employed contains more
than 50% amylose.
6. The process of claim 1 wherein a salt selected from the group
consisting of ammonium sulfate, ammonium monobasic or dibasic
phosphate, magnesium sulfate, sodium sulfate and mixtures thereof
is additionally present in the starch slurry.
7. The process of claim 6 wherein the salt is present in an amount
of 10 to 20% by weight of the slurry solids.
8. The process of claim 6 wherein the starch contains less than 50%
amylose.
9. The process of claim 6 wherein the salt if ammonium sulfate or
ammonium phosphate and the pH of the slurry is adjusted to a pH of
8 or below.
10. The process of claim 6 wherein the salt is magnesium
sulfate.
11. The process of claim 1 wherein the pressurized starch
dispersion resulting from step (2) is piped to a vertical flash
chamber to separate the gas components and degas the liquid
starch.
12. The process of claim 1 wherein the chilled surface is a
revolving drum.
13. The process of claim 1 wherein the chilled surface is a
continuous belt.
14. A process for the encapsulation of dimethyl anthranilate in a
starch matrix comprising the steps of:
(1) slurrying the starch in water;
(2) thoroughly dispersing the starch in the slurry by injecting
steam at a pressure of at least 110 psi into the slurry to raise
its temperature to 120.degree. to 180.degree. C. at a pressure of
55-120 psi or above;
(3) adding dimethyl anthranilate to the dispersion and effecting
intimate mixing of the latter therein;
(4) spreading the resultant mixture on a chilled surface;
(5) recovering the encapsulated material in sheet form; and
(6) cutting or grinding and drying the resultant matrix of starch
and encapsulated material.
15. A process for the encapsulation of aspartame in a starch matrix
comprising the steps of:
(1) slurrying the starch in water;
(2) thoroughly dispersing the starch in the slurry by injecting
steam at a pressure of at least 110 psi into the slurry to raise
its temperature to 120.degree. to 180.degree. C. at a pressure of
55-120 psi or above;
(3) adding aspartame to the dispersion and effecting intimate
mixing of the latter therein;
(4) spreading the resultant mixture on a chilled surface;
(5) recovering the encapsulated material in sheet form; and
(6) cutting or grinding and drying the resultant matrix of starch
and encapsulated material.
16. The process of claim 14 wherein a salt selected from the group
consisting of ammonium sulfate, ammonium monobasic or dibasic
phosphate, magnesium sulfate, sodium sulfate and mixtures thereof
is additionally present in the starch slurry.
17. The process of claim 16 wherein the salt is present in an
amount of 10 to 20% by weight of the slurry solids.
18. The process of claim 15 wherein a salt selected from the group
consisting of ammonium sulfate, ammonium monobasic or dibasic
phosphate, magnesium sulfate, sodium sulfate and mixtures thereof
is additionally present in the starch slurry.
19. The process of claim 18 wherein the salt is present in an
amount of 10 to 20% by weight of the slurry solids.
Description
The present invention is directed to a method for the encapsulation
of materials in a matrix composed of unmodified or modified starch,
starch flour or cereal under conditions that reduce or eliminate
the decomposition and/or loss of the material being
encapsulated.
Many methods have been employed in the prior art to encapsulate a
variety of materials. In general, the specific method employed as
well as the encapsulating agent utilized has been dependent on the
type of material being encapsulated. Thus the volatile or
non-volatile nature of the material as well as its water or oil
solubility have been the principal factors controlling the method
of encapsulation and the encapsulating materials chosen.
SUMMARY OF THE INVENTION
We have now found a method for encapsulating virtually any material
regardless of volatility or solubility using starch as the
encapsulating agent.
In accordance with the present invention, the materials to be
encapsulated are combined with a high temperature-stabilized
dispersion of starch, optionally containing salt. The
temperature-stabilized starch dispersion acts as a protective
colloid, encasing the material to be encapsulated. Upon subsequent
rapid cooling of this mixture on a chilled rotating drum, the
starch polymer chains collapse upon themselves, forming a firm
sheet and encapsulating the core material. The sheet can then be
cut, chopped or sliced in the wet state, then dried and ground to
yield particles. in the resultant product, the material being
encapsulated is evenly distributed throughout the starch
matrix.
Thus, the encapsulation process of the present invention comprises
the following steps:
(1) slurrying the starch in water, optionally in the presence of
salt;
(2) thoroughly dispersing the starch in the slurry by injecting
steam at a pressure of at least 110 psi into the slurry to raise
its temperature to 120.degree. to 180.degree. C. at a pressure of
55-120 psi or above;
(3) adding to the dispersion the material to be encapsulated and
effecting intimate mixing of the latter therein;
(4) spreading the resultant mixture on a chilled surface such as a
chilled revolvig drum or a continuous belt;
(5) recovering the encapsulated material in sheet form; and
(6) cutting or grinding and drying the resultant matrix of starch
and encapsulated material.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A wide range of materials may be encapsulated using the process
disclosed herein. The only limitations with respect to the core
material to be encapsulated are that it not react with water or
salt, if present, or irreversibly with starch, and that it be
stable for short periods at the elevated temperatures employed.
Thus, it is possible to encapsulate water soluble materials as well
as some low boiling materials which have adequate stability for the
very short time for which the materials are exposed to the elevated
temperatures of the starch dispersion. Representative materials
include flavors and seasonings such as flavoring oils; natural and
artificial sweeteners such as aspartame; pigments; metallic
powders; latices; oils; plasticizers; herbicides; insecticides;
fumgicides; nematicides; bacteriocides; rodenticides;
molluscicides; acaricides; larvacides; fumigants; animal
repellants; insect repellants; plant growth regulators;
fertilizers; pheromones; odor producing compositions; catalysts;
adhesives; pressure sensitive color formers; electrostatographic
toners; pressure rupturable lubricants; antifoulants; phase change
materials; fire extinguishers; corrosion inhibitors; defoamers;
sizing agents; thickeners; unsaturated fats and acidulants,
sub-cutaneous medications, etc. Depending upon the type of core
material employed, from as little as 0.1% to as much as 80% by
weight core material (based on solids of starch plus core material)
may be encapsulated in the starch matrix.
The benefits of the present invention are particularly exemplified
in the encapsulation of dimethyl anthranilate, a non-toxic food
flavoring that is repellant to birds and has a high volatility at
ambient temperatures. Heretofore, this high volatility has
prevented its use as a bird repellant in animal foods and natural
environments. Some methods have been proposed for spray-drying the
dimethyl anthranilate with dextrin or other modified starches. Such
spray-dried, encapsulated dimethyl anthanilate has two major
drawbacks; first, it is water soluble, making it unsuitable for
application in natural environments with the potential of rainfall
and high humidities would cause the untimely release of the bird
repellant.
In contrast, when dimethyl anthranilate is encapsulated using the
methods described herein, it can be encapsulated in a water
insoluble starch matrix which will provide a controlled rate of
release of the bird repellent over a period of about 30/40 days at
20.degree. C./50% relative humidity or at 40.degree. C./90%
relative humidity.
The process of the invention is not limited to any specific starch
encapsulating materials. Corn starch, rice starch, potato starch,
tapioca starch, wheat starch, amylose or amylopectin fractions may
be employed. The starch base may be used in modified or unmodified
form. The choice of the starch to be used is dependent in large
part on the end use of the encapsulated material particularly the
mechanism and desired rate of release, if any, of the material from
the encapsulating matrix.
In addition to the use of starch as the encapsulating material,
water soluble hydrocolloids such as polyvinyl alcohol,
carboxymethylcellulose, hydroxyethylcellulose, polyacrylic acid and
polyvinyl pyrrolididone may replace up to 50% of the starch
component.
Although not theoretically required to effect encapsulation
according to the present invention, the addition of salt to the
starch slurry results in more efficient formation of the sheet on
the chilled surface, especially in the case of starches containing
relatively low levels of amylose. As an example, the use of high
amylose starches (i.e. those containing more than approximately 50%
amylose) in the absense of salt allows the formation of a firm
(set) sheet in 2 or 3 seconds, permitting the sheet to be doctored
off the chilled surface after this brief period. In contrast, the
use of corn starch without added salt requires 10 to 15 seconds for
adequate set; hence, the speed of rotatio of the drum or movement
of any other chilled surface must be regulated accordingly. Other
starches which require even longer set times would therefore not be
useful on a practical basis without the addition of the salt.
Suitable salts for this use include ammonium sulfate, ammonium
monobasic or dibasic phosphate, magnesium sulfate, sodium sulfate
and mixtures thereof.
While there is no requirement regarding the selection of any of the
above components used in the process, once they are determined the
ratios of the components are interrelated. Thus, the need for as
well as the ratio of salt, starch and water in the slurry are
dependent upon the starch selected. As discussed previously, those
starches containing high levels of amylose require little or no
salt to effect efficient setting on the chilled surface while
amylopectin based starched or dextrins may require saturated or
super-saturated levels at the exit temperature. Similarly, the
level of amylose in the starch affects the choice and concentraion
of the salt required for efficient precipitation, with the higher
amylose containing starches capable of forming a firm sheet with
any concentration of any of the salts mentioned above, while the
starches with lower levels of amylose require higher levels of the
preferred salts such as ammonium sulfate and magnesium sulfate for
efficient precipitation rates. The amount of starch usually varies
from about 20 to 40% by total weight of the slurry (starch, salt if
present and water). The amount of salt employed should be kept as
low as possible, generally in the range of 10 to 20% by total
weight of the slurry (starch, salt if present, and water) since
some of the salt employed will remain in the final starch matrix.
In all cases, the levels of the components should be such that the
starch/salt/water ratio does not cause retrogradation prior to
setting on the chilled surface.
In general, the process of the invention involves the following
steps, all of which may be conducted in a continuous manner.
First, a slurry of starch (and any hydrocolloid or salt desired),
is formed. If ammonium sulfate or ammonium phosphate is used, it
may be necessary to add an acidic material to lower the pH to 8 or
below. No pH adjustment is needed if magnesium sulfate is the salt
used as it is effective under both acidic and basic conditions.
The temperature of the slurry is then raised via steam injection to
a temperature high enough to thoroughly dispersed and cook the
starch. This temperature is generally in the range of 120.degree.
to 180.degree. C. at a pressure of 55 to 120 psi or above,
preferably 130.degree. to 165.degree. C.
In accordance with a preferred embodiment, the pressurized starch
dispersion is piped to a vertical flash chamber sized and
constructed so that the liquid readily flows to the bottom and the
gas (i.e. excess steam and entrained air) cleanly separates at the
top. The gas is then vented through an adjustable relief valve, the
setting of which controls the pressure in the flash chamber and
consequently the temperature of the starch dispersion. While not
essential, the latter step provides a useful process control by
reducing and controlling the cooked starch temperature to a
preferred range of about 105.degree. to 120.degree. C. for the
remainder of the process. It also degasses the starch dispersion so
that foaming at the drum or on any other chilled surface and
dilution is reduced and accurate metering of the starch is
facilitated.
After the starch has been thoroughly cooked and preferably
degassed, a metered flow of the core material (i.e. the material to
be encapsulated) is added. While the core material could have been
added to the starch dispersion initially or at some earlier stage
in the processing, its addition at this point where the temperature
of the starch dispersion is lower than that required to cook the
starch and at a point nerer to the chilled surface reduces the
exposure of the core material to both the maximum temperature and
time at that elevated temperature allowing encapsulation of heat
sensitive or volatile materials which could not have been otherwise
encapsulated. Further, since the oxygen levels have been reduced by
the extraction of vapor phase steam before injection of the core
material, there is little risk of oxidation of easily oxidized core
materials. The starch dispersion and core material are intimately
mixed by piping through a static mixer. In the case of oily core
materials, a turbine emulsifier or similar means may be required to
evenly distribute fine oil droplets throughout the starch cook.
The resulting mixture is then spread on a chilled moving surface
maintained at a temperature of below about 15.degree. C. Here, the
starch rapidly retrogrades to a firm sheet, trapping all the other
components with little or no synerisis (weeping) of water or salt
solution. Due to the rapid set of the high solids starch used in
this process, time in contact with the chilled surface need only be
on the order of seconds. This allows use, for example, of small
diameter drums (approx. 2 ft.) or short runs of chilled belt and
permits high rates of production. The sheet can then be cut, ground
or extruded with minimum loss of the encapsulated core material and
then dried. If salt has been employed, it may be desired to wash
the salt from the resultant ground encapsulated material.
The release characteristics, i.e., the ability of the encapsulated
core material to be released from the starch matrix, can be varied
by the practitioner to permit fairly rapid release by using an
undried, low amylose, high moisture particulate mass to a very slow
release rate using a dried, high-amylose starch film. Similarly,
the temperature at which the release will be effected can be varied
from as low as about room temperature using a dextrin based starch
to over 90.degree. C. using a high amylose starch base.
Since the resultant dried matrix can be resistant to acid and
alkali, (depending on the starch used) further modifications can be
made. Thus, it is possible to react the matrix with crosslinking
agents or cationic or anionic groups or it can be oxidized or
chemically modified in other ways without affecting the core
material encapsulated therein.
In the following examaples, which are for illustrative purposes
only, all parts are by weight and all temperatures in degrees
Celsius unless otherwise noted.
EXAMPLE 1
Encapsulation of a Volatile Solvent with Controlled Release
A slurry of the following composition was made:
______________________________________ high amylose (70%) corn
starch 38 parts water 62 parts
______________________________________
This slurry was cooked at 175.degree. C. and 35 percent solids, and
then piped to a vertical flash chamber. On entering the flash
chamber the steam pressure used during cooking was reduced to less
than 10 psig and consequently the temperature reduced to
105.degree.-110.degree. C. Steam vapor was separated from the
starch by gravity and vented through a spring loaded relief valve.
The de-gassed starch was metered into a static mixer.
Simultaneously, liquid heptane (boiling point 100.degree. C.) was
metered into the starch upstream of the static mixer.
After passing through the static mixer the blended starch/solvent
mix was passed through a turbine pump. The average size of the
heptane droplets was reduced by the shear action of the pump to a
range of approximately 1-5 microns.
The temperature of the heptane and surface heat loss from the
piping was controlled so that the temperature of the starch/heptane
emulsion was 78.degree.-82.degree. C. on exiting the turbine pump.
At this temperature only a small percentage of the heptane was
present as vapor and the vast majority of the vapor was retained,
entrained in the viscous liquid starch cook. Transit time between
heptane point of addition and exiting the turbine pump was only 3-4
seconds due to the short lengths of pipe involved.
After exiting the turbine pump the starch emulsion was rapidly
piped to an applicator mounted on a rotating chilled metal drum.
This applicator consisted of a longitudinal half-section of pipe
mounted transversely across the drum surface with the open side
against the drum and the leading edge and sides sealed against the
drum. The trailing edge had an adjustable blade at an obtuse angle
to the drum's surface. As the starch/solvent emulsion was pumped
into the applicator it was spread by the blade into a thick film
with the thickness controlled by the blade clearance; the width by
drum speed and rate of starch feed. The starch emulsion pool volume
inside the applicator was adjusted so that dwell time was less than
a second. Since the starch rapidly cooled in contact with the
chilled drum after the film was spread, this dwell time was the
sole exposure of core material to heat, at atmospheric pressure,
using this process. Upstream, the starch/core material emulsion was
under pressure in piping. Downstream of the applicator the core
material was contained in a cold retrograded starch matrix. This
short dwell time has obvious advantages when encapsulating heat
sensitive, oxygen sensitive or volatile core materials.
A doctor blade was mounted on the drum to remove the chilled and
set starch/core material film. This rapidly set film, after cooling
by contact with the chilled drum; was firm, non-tacky, mechanically
stable, and at or near room temperature. The injected core material
was uniformly dispersed throughout the interior of the film with no
free liquid water present; all water in the de-gassed cook, from
either slurry makeup or injected as steam, was retained in the firm
retrograded starch film.
The material was manually diced into one quarter inch cubes, then
dried in a lab-scale forced air drier (Moisture Teller, Harry W.
Dietert Co.) for six minutes at 60.degree. C. The dried product
consisted of hard opaque-white chips with a faint odor of
heptane.
This dried product was analyzed by gas chromatography and found to
contain (8%) heptane on dry starch. The following extraction
procedure was used to prepare the GC samples: 2 g of air dry
starch/heptane matrix was dissolved in 19 g dimethylsulfoxide
(DMSO) in a sealed vial using gentle heat. The DMSO solution of
starch was cooled and 10 g of methylene chloride (containing 0.1%
chloroform for use as an internal GC standard) was added to
precipitate the starch. Next, 2 g water was added to destabilize
the DMSO/methylene chloride solution. On addition of water two
phases separated, the lower was methylene chloride was heptane, the
upper was DMSO and water. Control extractions, using dried cooked
starch with added heptane showed complete recovery of the heptane
in the methylene chloride phase.
An aliquot of the lower phase was analysed using a Hewlett Packard
Model 5890 gas chromatograph to determine heptane concentration. A
HP-1 capillary column 10 meters by 0.53 mm with methyl silicone gum
stationary phase was used. Sample size was 1 microliter. Injector
sample split was 98:2. Temperature programming was: 50 C., 2 min;
25 degrees per min rise to 300 C.; hold at 300 C., 5 min. Dried
heptane containing starch chips were exposed at room temperature in
a single thickness layer. Samples were taken daily and analysed by
the above procedure. Time for 50% loss of this unencapsulated
heptane in the form of control batches of 10% heptane adsorbed on
granular starch averaged 2.9 minutes while time for 50% loss of the
encapsulated heptane was approximately 12 days.
Completely decoupled carbon-13 Nuclear Magnetic Resonance analysis
showed that the heptane was present in the dried starch matrix,
either totally or in the great majority, as discrete droplets of
liquid, several microns or less in diameter.
EXAMPLE 2
Encapsulation of Water Soluble Dye
A 30 percent slurry of corn starch (70% amylose) with 10% Napthol B
green dye (on starch weight) was jet cooked at 150.degree. C., the
pressure reduced to less than 10 psig and the steam vapor separated
from the liquid starch. The degassed starch was metered onto a
chilled rotating steel drum through an applicator box. As the
starch was spread on the drum's surface its temperature dropped in
less than two seconds from approximately 110.degree. C. to less
than 38.degree. C. As a result of the temperature drop the starch
set to a continuous sheet of firm gel, without any free liquid. The
resulting dark green sheet was cut to pieces 10-20 mm long, 3 mm
wide and approx. 0.5 mm thick. They were oven dried to
approximately 12% moisture. Rate of release in water was determined
by adding a weighed portion of dried starch containing the entraped
napthol green to a known volume of water. The reduction in
transmittance at 520 nm due to release of dye was measured with a
Brinkmann C-800 colorimeter; a 2 cm probe was used. The
unencapsulated Naphthol B green dye dissolved immediately in water
while the encapsulated dye released slowly, over time, in a
controllable manner.
EXAMPLE 3
Encapsulation of Food Flavoring Oil with Reduction of Handling
Hazard
Oil of Capsicum (the extracted active agent in hot peppers) is a
required ingredient in many highly spiced foods; however, it can be
a handling problem since the concentrated strengths used for
flavoring by the food industry can cause severe skin and mucous
membrane irritation. An additional concern with Capsicum Oil is the
retention of uniform strength during storage. Encapsulation in
starch can reduce these problems by containing the oil in a free
flowing granular powder with little free surface oil; volatiles are
retained (and oxidation should be reduced).
These benefits were demonstrated by jet cooking high amylose (70%)
corn starch at 30% solids, mixing a 50 gram portion of the hot cook
in an Epenbach mixer (Ace Scientific supply), adding 4.5 grams of
capsicum oil (500,000 heat units/gram, commercial sample) with
0.045 g sodium stearoyl lactylate to form an emulsion, and casting
a film from the emulsion in a chilled aluminum pan simulating a
chilled casting surface. The emulsion rapidly set to a firm
flexible dark red sheet with a faint hot pepper odor. This sheet
was cut into one eighth inch cubes and Dietert dried for ten
minutes at 48.degree. C. The resulting products were hard
free-flowing dark red cubes with only a very faint pepper odor. The
cubes were almost completely free of surface oil unless crushed and
could be handled safely.
To further evaluate the encapsulation procedure, the dried product
was solvent extracted, using a soxhlet extraction apparatus, with
four sequential solutions: acetone, 4:1 acetone/water, 5:1
methanol/water, and acetone. The solvents were combined, vacuum
stripped, and the extracted capsicum oil weighed. The extractable
oil was 69.6% of the oil added to the cooked starch. Recovery was
not complete, as there was residual color and odor in the extracted
starch matrix.
EXAMPLE 4
Encapsulation of a Solid
A starch slurry was made of the following composition:
______________________________________ High amylose (70%) corn
starch 32.6 parts Calcium Carbonate (Hydrocarb 65, Omya) 16.3 parts
Water 51.1 parts ______________________________________
The slurry was jet cooked and applied to a chilled rotating drum as
in Example 1. The product was a white film continuous sheet. It was
pelletized by being forced through a 20 mesh screen and Dietert
dried. The dried product consisted of white prills approximately 1
mm diameter by 2-3 mm long.
The encapsulating starch provides the core material with a degree
of protection against attack by acid solutions and may be used to
provide controlled release. This was demonstrated by placing the
dried material described above in pH 4.0 hydrochloric acid solution
at 25% solids on total, and measuring the dissolved calcium in
solution over time. The pH was controlled at 4.0.+-.0.1 by an
automatic pH controller (Analytical Measurements Inc.) which
metered additional 0.25N hydrochloric acid into the slurry via a
Masterflex peristaltic pump. Samples of the slurry were taken,
immediately filtered, and dissolved calcium determined by titration
with ethylenediamine tetraacetic acid sodium salt (EDTA) (Method
309B, 14th Ed. Std. Methods for Examination of Water and Waste
Water, Am. Public Health Assoc.).
A control blend of calcium carbonate and raw high amylose corn
starch was exposed at pH 4.0 in an identical manner. Eighty percent
(80%) of the unencapsulated calcium carbonate dissolved in less
than one minute; however the encapsulated calcium carbonate
required approximately 17.4 hours to release the same amount.
EXAMPLE 5
Encapsulation of a Volatile Oil Using Salt
An industrial masking scent (NJ 1838, PPF, Inc.) was encapsulated
using a variation of the method described in Example 1.
______________________________________ Two suspensions were made:
______________________________________ Mixture A: Water 33.4 parts
High amylose (70%) corn starch 18.8 parts Ammonium Sulfate 9.4
parts Mixture B: Water 15.4 parts Purity Gum BE (a cold water 7.8
parts soluble 80 water fluidity amioca dextrin treated with 3%
octenyl succinic anhydride available from National Starch and
Chemical Corp.) PPF NJ 1838 Fragrance Oil 15.4 parts
______________________________________
Mixture A was made with simple low speed blending. Mixture B was
made by adding the components, in the order listed, to a beaker
with continuous high shear agitation (Dispersator, Premier Mill
Corp.) to form a 5-10 micron emulsion of the oil. Part B was then
added to part A with gentle agitation.
The suspension of raw starch and CWS starch/oil droplets in salt
solution produced by combining parts A and B was jet cooked at
150.degree. C., vented to atmospheric pressure and degassed, and
applied to a chilled drum as described above.
The resulting product was a firm flexible sheet. All the water
present in the degassed cook was contained in the sheet; there was
no free liquid. The wet sheet had a strong odor characteristic of
the fragrance oil. Microscopic examination showed the oil to be
present as droplets 1 micron diameter or less trapped in the starch
matrix.
The sheet was readily cut into 1/4 inch flakes. They were dried in
a Dietert Moisture Teller at 38.degree. C. to approximately 20%
moisture. These flakes had a persistent odor characteristic of the
fragrance oil. The flakes were free-flowing and non sticky.
After the flakes had come to equlibrium room temperature moisture
(about 12%) they were analyzed for volatiles using a Dupont
Instruments Model 951 Thermo-Gravimetric Analyser. Analysis showed
that approximately 60% of the oil in the original slurry was
retained in the dried flakes.
EXAMPLE 6
Encapsulation of Dimethylanthranilate
High amylose starch (Hylon VII, National Starch and Chemical) was
slurried in water at 35 percent anhydrous solids. Sodium stearyl
lactylate was added to a concentration of 0.1 percent on total
weight.
This slurry was processed through the jet cooking and drum casting
equipment previously described. Temperatures in the jet cooking
stage were 175.degree.-180.degree. C. Flash chamber temperatures
were maintained at 120.degree.-125.degree. C. Dimethylanthranilate
(DMA) was metered into the hot starch cook after the flash chamber
at a rate chosen to give 30 percent DMA on anhydrous starch and DMA
weight. The DMA/starch mix was emulsified in-line using a turbine
pump. Exit temperature after emulsification was
85.degree.-92.degree. C.
The starch DMA emulsion was spread by an applicator blade onto the
surface of a chilled drum in an approximately 1/4th inch coating.
It rapidly set to a firm opaque white sheet. The cool sheet was
removed from the drum by a doctor blade and cut to approximately
1/4 inch cubes with a Comitrol cutter (Ureschel Laboratories).
These cubes were dried in a Uni-Glatt fluid bed dried (Glatt Air
Techniques).
Composition of the dried was shown by analysis to be:
______________________________________ Starch 62.3% (on total
matter) DMA 24.7% (28.4% on dry matter) Water 13.0%
______________________________________
94 percent of the added DMA was retained in the dried sheet.
When 10 grams of the encapsulated DMA were stored in 100 ml of
distilled water for 7 days, only 9% of the encapsulated material
was lost.
EXAMPLE 7
Encapsulation of Aspartame
High amylose starch (Hylon VII National Starch and Chemical) was
slurried in water at 30% anhydrous solids.
The slurry was jet cooked at 150.degree. C. A portion of the hot
cooked starch was placed in a Waring Blendor and Aspartame (The
Nutrasweet Co., Skokie, Ill.) added at a level of 15% on starch.
After 30 seconds mixing the aspartame was thoroughly mixed into the
starch. It was then spread as a thin layer in chilled metal pans to
simulate drum casting and rapidly set into a firm sheet. The cooked
sheet was diced and dried in a Dietert dryer at 68.degree. C. for
45 minutes. The dryer encapsulated aspartame was ground to less
than 200 mesh using a Moulinex coffee mill.
Lab scale batches of chewing gum were made incorporating the 200
mesh encapsulated aspartame at 0.15% aspartame on total and a
control using unencapsulated aspartame. An eight member taste test
panel found in blind testing that the gum containing the
encapsulated aspartame produced a sweet taste from one to 15
minutes longer than the control.
Now that the prefered embodiments of the present invention have
been described in detail, various modifications and improvements
thereof will become readily apparent to those skilled in the art.
Accordingly the spirit and scope of the invention are to be limited
only by the appended claims and not by the foregoing
specifications.
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